327 build/advice

Hi guys. This is my first post and I want to say hi to everybody and thanks in advance. I'm a novice engine builder but am smart enough to do lots of homework and ask for help from more knowledgeable people than me. I'm looking for some advice on building a pump gas Hydraulic roller 327. I have researched a lot of the 60's era builds but they were all 11:1 compression motors with solid cams (30 30 cams). I'm looking to get about 425 HP and even more important as much torque and mid range power that I can get out of this mighty mouse on pump gas (9.5:1 compression). This will be a 80% street vehicle (and yes before anyone says it, I know that I could get more power out of a 350 or 383 but everybody have those and i want something different. I have built a 350 but have always been interested in the mighty mouse 327's ...plus a 327, would be more correct to the truck it's going in) Here's what I have. I have a 1966 Chevy short-wide PU. It has a 12 bolt with 3.73 gears with a 700R4. I'm going to have about a 2000-2500 stall. I have a 68 327 block with forged crank that unfortunately will have to go to .060 over to be cleaned up. The block is at the machine shop as we talk getting bored, aligned honed, decked to .010, and balanced. I thought about going with a 6" rod but have decided to stay with 5.7's. To get my compression ratio right (about 9.5:1), I'll be using forged flat top pistons (probably Speed Pro brand) with Moly rings, machine shop owner is going to recondition some forged i beam connecting rods (he builds a lot of circle track cars and some customers replace them after one use but he guarantees that they are good). I will be using ARP rod and main bolts. Machine shop owner recommended following cam XE294 HR from Comp cams. it's duration at .050 is 242 (intake) and 248 (exhaust) with 110 degree lobe separation and valve lift of .54 (intake) and .562 (exhaust). I have always used hydraulic flat tappet cams but was told that a roller could take more duration. This will mainly be a street truck (no AC but possibly could have some day) so I don't want to accidentally put to much cam in it like a lot of people do. Does this cam look OK to you guys? As far as the heads, I'm looking at the Dar SHP, Aluminum, Assembled, 72cc Chamber, 200cc Intake Runner Cylinder Heads. They have 2.02 intake and 1.6 exhaust valves. (I don't know if I should go with a smaller intake runner size 185 cc or larger ones like the 200 cc or 215 cc. Can someone explain this too me? These heads are assembled but I will match springs to cam. I plan on using an Edelbrock Performer RPM Air Gap intake (1500 to 6500 rpm). I have two carburetors to choose from. I have a Holley 4150 750 Double Pumper or a 600 cfm Edelbrock. I'm thinking the Holley 750 might be best. Anyways, guys any and all advice would be appreciated. Thanks

On the cam, that one is big but with your stall, deep first gear, and rear gears you might be okay. It'll want more rpm before it hits its sweet spot and that shouldn't be a problem because the 327s like to rev. Dropping 10* may be better suited to street use. A cam of given duration will act smaller in a 400cid motor than it will in a 300cid motor. That 242 cam would be large in 383, in a 327 it's going to be radical.

IMO the 185 heads would be better because the motor is smaller, relatively. The bigger the port volume in the heads, the more volume of air you have to get moving before you have velocity of movement. Then again if you plan on running it to 7500rpm regularly go with the 200cc heads.

On the carburetor, I have learned to use the AFBs and Holleys have near infinite tuning. If you plan on running it to 7500rpm, the 750 will better suit your combination.

When I built my 327 I used vortec heads. I bought them straight from gm. I had the valve guides cut down and I used the largest xtreme 4x4 flat tappet cam comp offered. Is it fell in right at 9:1 compression, and it pushed my 3700lb truck into the mid 13s in the quarter. It was a very strong running engine.

again I'm a novice ...but why did the valve guides need to be cut down and do you have the cam specs? How does lift numbers on a hydraulic roller compare to that of a hydraulic flat tappet? apples to oranges?

I'm at work right now so ill post all the specs of my 327 when I get home tonight, but as for cutting down the valve guides vortec heads in stock form will only allow for a .480 max lift. The cam I used was .498exhaust .480 intake so I had the valve guides trimmed to clear the slightly larger cam.

I built me 327 starting out with a .30 bore, stock rods with arp wave lock bolts, flat top pistons, I always have it balanced and highly recommend it. Using vortec heads with 64cc chambers and a .015 head gasket brought my compression to 9:1 and the quench to .035. A tight quench is important in any performance engine. Weiand steath intake with a holley 650 double pumper. The cam was a comp xtreme 4x4. 270/278 advertised 226/234 at .050. .480/.498 lift. 111 degrees lobe separation. In an 85 c10 with a nv3500 5 speed and 3.55 gears weighing in at 3700lbs it run 13.50s. If I could do it again I would have bought the RHS pro torker vortec heads and a small dome to get 10:1 compression and run the comp xtreme 4x4 roller cam 280/284 advertised 230/234 at .050. .474/474 lift. 111 degrees lobe separation. But with 1.6 Rockers to push it to .505 lift. I think that combo would easily get you to your 400+ HP goal.

OK, I've changed my build up some. Let me know what you guys think of this combination and please offer ant suggestions you might have. I am now going with a hydraulic flat tappet instead of roller (couldn't justify hp gain to cost). I chose the Comp Cams XE 274 (230 intake and 236 exhaust @.050). I'm going to put some Brodix IK 180 aluminum cylinder heads (70 cc and 180 intake runners)with some mild porting and polishing. I'm also going to use a gasket matched Brodix HP 1 intake manifold with a Holley DP 750 on top. I was told that I'm probably gonna need to put smaller jets in. I'm using Speed Pro forged Aluminum flat-tops (+5.4 cc) pistons and had my block decked to .010. If my figures are right using a .041 head gasket, this will give me about a 9:5:1 compression ratio. I'm hoping that this combination will get me about 425 hp and about 400 ft lbs of torque. The block and rotating assembly is at the machine shop getting balanced and final hone. It won't be long before I can start building this mighty mouse. I'm so excited I can't hardly stand it. I love hearing a motor come to life!!!

Help, I've got another question. Did 68 large journal blocks use small journal main bolts? Machinist told me that ARP 123 5001 were wrong and that I need ARP 134 5002 (which is for small journal). I know they changed blocks up in 68 and that they changed from small to large journals (well actually medium if u count 400 sbc) from 67 to 68. They also changed blocks again in 69 with 350 and last yr for 327. Are all 68 blocks this way or could this have been left over main bolts they put in my motor? I just thought it was strange. Has anyone heard of this?